Since 1960, a major interest of the Clinic of Surgery, NHLBI, has been the development of an operative method to relieve obstruction to left ventricular outflow in patients with idiopathic hypertrophic subaortic stenosis (IHSS). As of May 1, 1977, 173 patients have been operated upon in this Clinic. At operation, a wedge of left ventricular septum is resected. The operative mortality has been low, as has the incidence of major operative complications. One hundred thirty-eight patients have undergone detailed postoperative evaluation, including cardiac catheterization. There has been distinct symptomatic improvement in all survivors, and catheterization has confirmed partial or complete relief of obstruction in almost all patients. Long-term followup has not demonstrated recurrence of obstruction, and most patients continue to derive gratifying symptomatic and hemodynamic benefit. This experience demonstrates that wedge resection of the left ventricular septum in symptomatic IHSS patients with documented left ventricular outflow obstruction may be undertaken at low risk, and it provides long-term symptomatic and hemodynamic improvement.